Microsemi

Integrated Products Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

Page 1

Copyright

© 2000

Rev. 1.0, 2005-08-10

LX1672

Multiple Output LoadSHARE™ PWM

TM

®

DESCRIPTION

The LX1672 is a highly integrated

power supply controller IC featuring

two PWM switching regulator stages

with an additional onboard linear

regulator driver.

The two constant frequency voltage-

mode PWM phases can be easily

configured as a single Bi-Phase high

current output, two

independently

regulated outputs, or as a DDR memory

I/O supply with a tracking DDR

termination voltage supply. Power loss

and noise, due to the ESR of the input

capacitors, are minimized by operating

each PWM output 180° out of phase.

This

architecture

also

minimizes

capacitor

requirements

while

maximizing regulator response.

In bi-phase operation, the high

current output utilizes a patented current

sharing architecture, called Forced

current sharing without the use of

expensive current sense resistors.

This patented approach also gives

system designers maximum flexibility with

respect to MOSFET supply. Each phase

can utilize different supply voltages, for

efficient use of available supplies, while

programming the ratio of current pulled

from each using one of three methods (see

application section).

The

LX1672

incorporates

fully

programmable

soft-start

sequencing

capabilities.

Each output can be

configured to come up in any order

necessary as required by the application.

The LX1672 features an additional

Linear Regulator Driver output, which

when coupled with an inexpensive

MOSFET is capable of supplying up to 5A

for I/O, memory, and other supplies

surrounding

today’s

micro-processor

designs.

Each regulator voltage output is

programmed via a simple voltage-divider

network. The LX1672, utilizing MOSFET

RDS(ON) impedance, monitors maximum

current limit conditions, in each PWM

phase without the use of expensive current

sense resistors.

IMPORTANT:

KEY FEATUR ES

Up to Three Independently

Regulated Outputs

DDR Termination Compliant

Bi-phase Current Sharing

Outputs As Low As 0.8V

Generated From An Internal 1%

Reference

Multiphase High Current Output

Reduces Required Capacitance

Integrated High Current MOSFET

Drivers

300KHz, 500KHz and 600KHz

High Frequency Operation

Minimizes External Component

Requirements

Independent Phase Programmable

Soft-Start and Power Sequencing

Adjustable Linear Regulator Driver

Output

No current-sense resistors

APPLICATIONS/BENEFITS

Multi-Output Power Supplies

Video Card Power Supplies

DDR, VDDQ and Termination

Supply

PC Peripherals

Portable PC Processor and I/O

Supply

PRODUCT H I GHLIGHT

Memory Bus

....

DDR Termination

Memory Core

12V

3.3V

I/O

Graphics

Controller

DDR Memory

LX1672

Refer to Typical

Application for

complete circuit.

5V

PACKAGE ORDER INFO

PW

Plastic TSSOP

28-Pin

LQ

Plastic MLPQ

38-Pin

Switching

Frequency (kHz)

RoHS Compliant / Pb-free Transition DC: 0518 RoHS Compliant / Pb-free Transition DC: 0512

0 to 70

300

LX1672-03CPW

LX1672-03CLQ

0 to 70

500

LX1672-05CPW

0 to 70

600

LX1672-06CLQ

NOTE: Available in Tape & Reel. Append the letters “TR” to the part number (i.e. LX1672-06CLQ-TR)